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panfilero wrote:
> Hello,
>
> Does anyone know where I can find out how much current specific gauges
> of wire can handle? I've looked up web pages on it, but can't figure
> out what they mean... for example at
>
> http://www.interfacebus.com/Copper_Wire_AWG_SIze.html
>
> There's a column that says: Current Carrying, and another that says
> Fusing Current
>
> I'm interested in figuring out if 20 AWG wire can handle steady DC of
> 7.25 Amps, for 20 AWG is says
> Current Carrying: 1.46
> Fusing Current: 58.4
>
> ? I don't get what they're saying.... other websites have been
> similarly confusing..

Fusing current is pretty obvious isn't it ?

Also beware of operation at elevated temperatures and derate when bundled
or run in trunking.

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"panfilero" <> wrote in message
news:...
> Hello,
>
> Does anyone know where I can find out how much current specific gauges
> of wire can handle? I've looked up web pages on it, but can't figure
> out what they mean... for example at
>
> http://www.interfacebus.com/Copper_Wire_AWG_SIze.html
>
> There's a column that says: Current Carrying, and another that says
> Fusing Current
>
> I'm interested in figuring out if 20 AWG wire can handle steady DC of
> 7.25 Amps, for 20 AWG is says
> Current Carrying: 1.46
> Fusing Current: 58.4
>
> ? I don't get what they're saying.... other websites have been
> similarly confusing..
>
> Much Thanks

The current carrying capacity in the listed table is based on 700 circular
mills per amp, a very conservative number for wire wound inside a
transformer where heating is an issue.

The National electric code specifies current carrying capacity for open
wires or house wiring for example about twice that or 300 to 350 circular
mills per amp. This gives 20 AWG wire about a 3 Amp rating.

What is your application? What is the duty cycle? What is the thermal
environment, how hot can it get? Is it in a transformer or in open air and
how insulated? How much voltage drop can you tolerate?

On Mon, 08 Dec 2008 08:09:02 -0800, panfilero wrote:
>
> Does anyone know where I can find out how much current specific gauges of
> wire can handle? I've looked up web pages on it, but can't figure out
> what they mean... for example at
>
> http://www.interfacebus.com/Copper_Wire_AWG_SIze.html
>
> There's a column that says: Current Carrying, and another that says Fusing
> Current
>
> I'm interested in figuring out if 20 AWG wire can handle steady DC of 7.25
> Amps, for 20 AWG is says
> Current Carrying: 1.46
> Fusing Current: 58.4
>
> ? I don't get what they're saying.... other websites have been similarly
> confusing..
>
> Much Thanks

You didn't read the rest of the page:
"Current Notes:
The current shown per wire size listed above is based on 1 amp/ 700
Circular mils, other tables provide different current per wire size, and
different current for open air ~ check your local electrical code for the
correct current capacity [Ampacity]. The 1 amp/ 700 Circular mils seems
to be the most conservative, other sites provide/allow for 1 amp per 200
or 300 Circular mil. For shot wire lengths use 1A/200 Circular mil, for
longer wire runs use 300 Circular mil, and for very long wire runs use
the table above, 1 amp / 700 Circular mil.

The current rating is listed based on permissible voltage drop and not
conductor heating.

The ability of a wire to carry a given amount of current is affected by a
number of additional factors, which are not accounted for in the AWG
table above. The ambient temperature of the surrounding air, wire
insulation, and number of other wires bundled together [provided below].

Ampacity relates to the ability of the conductor to carry current [amps]
before the cable over heats. I understand there are hundreds of Ampacity
tables for many different conditions. The numbers above are but one
example. Ampacity Tables for many conditions:"

That's for *one wire in free air*, deratings for bundles (two wires
are a bundle), and altitude, of course, and the detailed calculations
are shown for various situations. May be available on the FAA dot GOV
website.

Mostly you'll not want to get anywhere near those current levels or
voltage drop will kill you.

On Tue, 9 Dec 2008, Peter Hucker wrote:
> Could someone buy Michael a sense of humour?
>
As soon as somebody buys you a clue. Your Siglines speak volumes -
someone not sure enough about the relevance of his posts that he has to
post a joke-de-jour as a sigline by way of an apology for his lack of
wit... If you have a relevant response to make, then make it - otherwise
leave this newsgroup to those who seriously want to discuss electronics!

? "Peter Hucker" <> ?????? ??? ??????
news...
> On Mon, 08 Dec 2008 17:06:55 -0000, Phil Hobbs
> <> wrote:
>
>> panfilero wrote:
>>> Hello,
>>>
>>> Does anyone know where I can find out how much current specific gauges
>>> of wire can handle? I've looked up web pages on it, but can't figure
>>> out what they mean... for example at
>>>
>>> http://www.interfacebus.com/Copper_Wire_AWG_SIze.html
>>>
>>> There's a column that says: Current Carrying, and another that says
>>> Fusing Current
>>>
>>> I'm interested in figuring out if 20 AWG wire can handle steady DC of
>>> 7.25 Amps, for 20 AWG is says
>>> Current Carrying: 1.46
>>> Fusing Current: 58.4
>>>
>>> ? I don't get what they're saying.... other websites have been
>>> similarly confusing..
>>>
>>> Much Thanks
>>
>> Back in the day, the usual rule of thumb for low-frequency power
>> transformers in continuous use was 1000 circular mils per amp, where a
>> 'circular mil' is the square of the diameter in mils (thousandths of an
>> inch), i.e. 1 circular mil = (pi/4) square mil. The 1000 circular mils
>> per amp rule comes out to 5.07e-6 square metres per amp.
>
> Mil is confusing. A lot of folk in metric countries say "mil" short for
> millimetre. A metre is considerably different to an inch.
>
No, we don't. We usually say mm.
Rough comparison:
#10->10 mm^2 , 35 A fuse for main residence
#12->6 mm^2, 25 A for stove
#14->4 mm^2, 20 A water heater
#16->2.5 mm^2, 16 Awashing machine, dishwasher
#18->1.5 mm^2, 10 A lighting
These figures are for one live conductor in a conduit inside the wall.
> P.S., what's a click?
>
> --
> http://www.petersparrots.comhttp://www.insanevideoclips.com
> http://www.petersphotos.com
>
> An infantry brigade was training in the summer heat, learning
> methods to counter Soviet offensive tactics. That summer, the
> area had experienced an infestation of rattlesnakes. Officers
> and NCOs were given one magazine of live ammunition to counter
> this danger, as several men had already been bitten.
>
> So much ammunition was expended shooting, supposedly, at
> snakes that the post commander demanded that every officer
> and NCO who had shot at a snake present the dead snake as
> proof that the expenditure of rounds was justifiable.
>
> The next day, the post commander entered his office and spotted
> a shoe box on his desk. He opened it, revealing a sleepy and
> sluggish, but very live, rattlesnake. Inside the box were twenty
> expended cartridges, and a short note. The note said, "I missed!"
When I was in Rhodes (east Greece), we were camping with my 542nd mechanized
infantry battalion, and there were lots of scorpions. We had brought a
wooden bank with us, and at bed time I saw a sergeant laying to sleep on the
bench. I asked, 'Is sir something wrong, I could help' he said just leave me
alone. I learnt from his colleagues that he found a scorpion under his
pillow (in his tent) and the "brave" sergeant decided to sleep on the bench.
Soldiers wished to be bitten, so that they could get sick leave.

Peter Hucker wrote:
> On Fri, 12 Dec 2008 19:18:11 -0000, Sjouke Burry <> wrote:
>
>> Rich Grise wrote:
>>> On Wed, 10 Dec 2008 18:32:54 +0000, Peter Hucker wrote:
>>>> Mil is confusing. A lot of folk in metric countries say "mil" short for
>>>> millimetre.
>>> Wrong. A mil is 0.001 inch (short for milli-inch); metric countries would
>>> have no reason to use it.
>>>
>>> Thanks,
>>> Rich
>>>
>> Wrong. Being in a metric country mil means millimeter.
>
> Some day the US will catch up with the rest of us?
>
Only when Easter and Christmas fall on the same day........